Update udev helper scripts to deal with device-mapper devices created
by multipathd. These enhancements are targeted at a particular
storage network topology under evaluation at LLNL consisting of two
SAS switches providing redundant connectivity between multiple server
nodes and disk enclosures.
The key to making these systems manageable is to create shortnames for
each disk that conveys its physical location in a drawer. In a
direct-attached topology we infer a disk's enclosure from the PCI bus
number and HBA port number in the by-path name provided by udev. In a
switched topology, however, multiple drawers are accessed via a single
HBA port. We therefore resort to assigning drawer identifiers based
on which switch port a drive's enclosure is connected to. This
information is available from sysfs.
Add options to zpool_layout to generate an /etc/zfs/zdev.conf using
symbolic links in /dev/disk/by-id of the form
<label>-<UUID>-switch-port:<X>-slot:<Y>. <label> is a string that
depends on the subsystem that created the link and defaults to
"dm-uuid-mpath" (this prefix is used by multipathd). <UUID> is a
unique identifier for the disk typically obtained from the scsi_id
program, and <X> and <Y> denote the switch port and disk slot numbers,
respectively.
Add a callout script sas_switch_id for use by multipathd to help
create symlinks of the form described above. Update zpool_id and the
udev zpool rules file to handle both multipath devices and
conventional drives.
The zpool_id and zpool_layout helper scripts have been updated to
use the more common /usr/bin/awk symlink. On Fedora/Redhat systems
there are both /bin/awk and /usr/bin/awk symlinks to your installed
version of awk. On Debian/Ubuntu systems only the /usr/bin/awk
symlink exists.
Additionally, add the '\<' token to the beginning of the regex
pattern to prevent partial matches. This pattern only appears to
work with gawk despite the mawk man page claiming to support this
extended regex. Thus you will need to have gawk installed to use
these optional helper scripts. A comment has been added to the
script to reflect this reality.
Some udev hooks are not designed to be idempotent, so calling udevadm
trigger outside of the distribution's initialization scripts can have
unexpected (and potentially dangerous) side effects. For example, the
system time may change or devices may appear multiple times. See Ubuntu
launchpad bug 320200 and this mailing list post for more details:
https://lists.ubuntu.com/archives/ubuntu-devel/2009-January/027260.html
To avoid these problems we call udevadm trigger with --action=change
--subsystem-match=block. The first argument tells udev just to refresh
devices, and make sure everything's as it should be. The second
argument limits the scope to block devices, so devices belonging to
other subsystems cannot be affected.
This doesn't fix the problem on older udev implementations that don't
provide udevadm but instead have udevtrigger as a standalone program.
In this case the above options aren't available so there's no way to
call call udevtrigger safely. But we can live with that since this
issue only exists in optional test and helper scripts, and most
zfs-on-linux users are running newer systems anyways.
By default the zpool_layout command would always use the slot
number assigned by Linux when generating the zdev.conf file.
This is a reasonable default there are cases when it makes
sense to remap the slot id assigned by Linux using your own
custom mapping.
This commit adds support to zpool_layout to provide a custom
slot mapping file. The file contains in the first column the
Linux slot it and in the second column the custom slot mapping.
By passing this map file with '-m map' to zpool_config the
mapping will be applied when generating zdev.conf.
Additionally, two sample mapping have been added which reflect
different ways to map the slots in the dragon drawers.
Add autoconf style build infrastructure to the ZFS tree. This
includes autogen.sh, configure.ac, m4 macros, some scripts/*,
and makefiles for all the core ZFS components.
Ned A. Bass
Brian Behlendorf